The best sushi restaurant you never heard of sits just east of the Hancock Center, coddles customers in whisper-quiet surroundings and seats all of 22 bodies when full, which it almost never is.

A restaurant this accomplished, especially one so small, so close to downtown and the city's biggest hotels, should have standing-room-only crowds and a three-week wait for reservations. There are a couple of reasons Masaki, a little more than a year old, isn't a tough table.

For one thing, its address on Mies van der Rohe Way, a street that stretches only four blocks in Streeterville, can confound cab drivers, a fact I learned the hard way. For another, it's expensive; the five-course tasting menu is $115, and the omakase — a chef's-choice assortment of mostly nigiri pieces — costs $96. One can hold the bill down somewhat by ordering a la carte (and there are a couple of worthy dishes available only this way), but this is no place for bargain hunters.

What your money does get you is excellent sushi and sashimi, magazine-cover presentations and the sort of attentive service that makes you feel like the only guest in the room. You also get more food than you expect: Each course of the tasting menu, for instance, consists of two side-by-side dishes — a clever marketer would call it a 10-course tasting — and there often are one or two extras (such as the amuse of glazed kabocha squash and skewered tamago) along the way. Dining at Masaki is like visiting a private club.

Owner Mauro Mafrici, who is chef/owner of the very good Italian restaurant Pelago (about 100 yards south of Masaki), opened Masaki because he thought the neighborhood needed a top-level Japanese restaurant.

"Honestly, it's such a small space, my wife (Kimberly) and I debated whether to open a Japanese restaurant or a wine bar," he said. "I'm very happy with what we did."

The first chef Mafrici hired for the restaurant ultimately declined to move to Chicago, so Mafrici looked around and snagged Osaka-born Jinwoo Han, who has spent the last 18 years in Chicago-area sushi restaurants. Han was the opening chef at the very good Bistro Nami in Clarendon Hills and also spent time at Nozumi in South Barrington and the late Blu Coral in Wicker Park. After nearly two decades working in restaurants accommodating 100-plus guests, Han says he's very happy to be in such an intimate setting.

"This is my smallest (restaurant), but also the finest," he says. "Now that I have only 22 seats, I can do a lot more."

That he does. Highlights from the five-course tasting included a beautiful, vertical assortment of king crab, octopus and sweet shrimp, offering a nice range of textures; the octopus pieces are almost frighteningly thick but cut so deftly that they're only slightly chewy. A long plate presents thinly sliced sea scallop with alternating slices of cucumber, dressed with a light sesame-yuzu vinaigrette.

Almost as pretty is the next course, a clamshell-shaped dish bearing a tiny floral arrangement, around which Han arrays slices of otoro (fatty tuna) and sake toro (salmon belly), and a ceramic tumbler holding an uni shooter. Next to that dish is a nigiri quartet of akami, madai, kampachi and hamachi toro, and as I inhaled these, it occurred to me that what Han serves as akami (his slices are much more flavorful than the insipid bright-red tuna offered elsewhere) is as good as others' chutoro.

The nigiri omakase began with a composition of cooked and raw madai (sea bream), the former in a shallow bowl of soup along with Manila clams and shrimp, and the latter a togarashi-dusted sashimi plate paired with fanned slices of Fuji apple. Then come a dozen nigiri pieces, progressing from light (madai, hirame) to fuller (glazed uni, octopus) flavors. In between was a piece of carefully carved squid nestling soft sea urchin, a terrific little bite.

The kitchen stumbles only with a couple of hot dishes. A beef sukiyaki and kushiyaki combination was highlighted by a sweet soy broth and tasty kabocha dumplings, but the beef in each was overcooked and dry. Overcooking also doomed the seared duck breast, an a la carte menu item, despite its pretty presentation.

Dessert is never a major part of Japanese cuisine, and, fittingly, it isn't a big deal here, but Han clearly makes an effort with his fruit plate, which includes nori-wrapped discs of citrus sorbet (yuzu, lime, grapefruit) and a fat squiggle of toasted meringue.

The beverage offerings are impressive, from the handful of craft cocktails to the wide selection of fairly priced sakes. There are good wines by the bottle or glass, although I'll quibble that the reds are too warm — possibly because, a few cooked dishes aside, the reds don't match well to the food.

Lunch is a nice option here: Han offers a two- and three-course lunch ($38 and $46, respectively), but plans to add a la carte options in the next month or so. Parking is tricky here, but Masaki offers discounted valet parking through the adjoining Hilton Chicago/Magnificent Mile Suites hotel (how's that for a mouthful?).